On 23/08/2021 08:16, Simon Gray wrote:
Thanks Dave, that is great to know!
Rght now I’m using one of the built-in OntModelSpec instances, calling
`setBaseModelMaker` and `setImportModelMaker` on it with an instance created by
`ModelFactory.createMemModelMaker` as the argument. It is my understanding that
I will then also have to extend (or implement) both a Reasoner, e.g.
org.apache.jena.reasoner.rulesys.OWLMicroReasoner, as well as a
ReasonerFactory, e.g. OWLMicroReasonerFactory to make fresh OntModelSpec
instance.
You shouldn't need to extend or implement a Reasoner.
I think you can simply create a reasoner instance - instantiate a
GenericRuleReasoner with the rules you want - and can then use
setReasoner on your copy of the OntModelSpec to install it for use.
Note that a reasoner can be reused multiple times - it's the
InfModel/InfGraph which holds all the reasoner state for a given
underlying base Model/Graph. The reasoner is just a reusable engine.
If you find that inelegant then you could indeed install a
ReasonerFactory (either the GenericRuleReasonerFactory passing in a
configuration model or create your own instance of a ReasonerFactory)
but I don't think that's necessary and certainly don't need to create a
new Reasoner class.
Dave
I wonder if this is the way to go?
Den 20. aug. 2021 kl. 17.24 skrev Dave Reynolds <dave.e.reyno...@gmail.com>:
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To create a reason with just a few rules of your choice then use the
GenericRuleReasoner. See
https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjena.apache.org%2Fdocumentation%2Finference%2Findex.html%23rules&data=04%7C01%7Csimongray%40hum.ku.dk%7C969da2c5af654732493b08d963eea058%7Ca3927f91cda14696af898c9f1ceffa91%7C0%7C0%7C637650698810113318%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=9vGnLU75Hl1sq%2FKe6vmBLthD9TKEoLBYvGIT%2F469P6w%3D&reserved=0
You can write your own rules or pick and choose from those in the source
code you've found.
To only compute the inverse relationships, and do so on demand, you
probably just need:
[inverseOf2: (?P owl:inverseOf ?Q) -> table(?P), table(?Q),
[inverseOf2b: (?X ?P ?Y) <- (?Y ?Q ?X)] ]
That is a "hyrid" rule (mix of forward and backward) see the docs, but
that's the default for GenericRuleReasoner anyway.
Dave
On 20/08/2021 14:01, Simon Gray wrote:
Hi everyone,
I'm on Jena 3.14 experimenting with the built-in OntologySpecs.
My main requirement is inferring reverse relations (when applicable). Only the
OWL reasoners do this, but they also infer so many more triples which balloons
the size of the InfModel so much that it is impossible for me to infer every
single triple within the memory constraints of my laptop. I have 16GB
available, with 12GB set aside for the JVM heap, but every attempt at copying
all inferred triples to a TDB2 model eventually fails with an OutOfMemoryError.
The dataset is a modest-sized WordNet.
I wonder if it's possible for me to create an OntologySpec with a Reasoner that
is a bit more basic, possibly only inferring reverse relation triples. Looking
into this, it seems like one needs knowledge of the Logic DSL used to define
the various built-in reasoners...? Or at least I never found an easy way to
create a Reasoner that just does this.
Maybe it's possible to use one of the built-in OWL reasoners and simply disable
some functionality? I'm not sure how, though. The only way I've found looking
at the source code and the documentation seems to be editing a .rules file
which contains the aforementioned logic DSL.
Kind regards
Simon
